A mobile communications system typically includes one or more base stations that may be connected by other network elements such as switches, or gateways. Each of these base stations provides radio coverage to a particular area, a so-called cell. Terminals within a particular cell coverage area establish a connection with the mobile communications system to one or more antennas of one or more base stations. The antennas are usually mounted on as high as possible structures, for example on roofs of houses and buildings, towers or masts.
The orientation of antennas and antenna structures can have a significant impact on the coverage, quality, capacity, and the maximum data rate of a wireless system. The influence of the antenna orientation onto the radio coverage is described for example in Esmael Dinan et al, “UMTS Radio Interface System Planning and Optimization”, Bechtel Telecommunications Technical Journal, December 2002, Vol 1, No 1, pp 1-10 or in Jaana Laiho, “Radio Network Planning and Optimization for UMTS”, Second Edition, John Wiley and Sons, 2006, Chapter 9 (Advanced Analysis Methods and radio access network auto-tuning), pp 505-569.
The optimization of the antenna orientation in radio systems provides a number of advantages, such as improving coverage, reducing the interfering emission (interference), an increase in range and/or an increase in the capacity of a cellular system.
To perform an appropriate optimization of antenna orientations, both in transmission and in reception case, it is necessary to determine the appropriate parameters (eg, received signal power, interference, data rate, bit error rate) at the receiver. In general, different ways of measuring these parameters exist, for example drive tests, reference receiver measurements, measurements at terminals—e.g. for each event, such as call set-up, handover, changing the strongest serving cell, etc. The measurements can be done during an active or passive connection, according to the respective standardized procedure. Today mostly standardized systems such as Global System for Mobile Communication (GSM), Universal Mobile Telecommunications System (UMTS) or Long Term Evolution (LTE) can be used for mobile radio transmission. However, the optimization of the antenna orientation is a problem that can occur with any and all mobile communication systems, no matter if standardized or proprietary.
The radio link, in which the antenna structure transmits to the receiving device, the user, is called downlink (or forward link). The reverse direction in which the antenna structure is on the receiving end and the signals are sent by the user (the mobile), in turn, called uplink (or reverse link).
In the downlink the path loss of the wireless channel can be determined by means of the respective measurement points (for example, using GPS localization during drive tests), and the position, orientation, and transmit power to the transmit antenna.
The received power derives from the transmitted power in the direction of the measurement point. Thus, it is highly dependent on the orientation of the antenna. The path loss (propagation characteristics of the mobile radio channel) is independent of the transmit power and can therefore be determined with knowledge of the transmit power, antenna orientation and structure (antenna gain), and the measured received power.
Based on the determined path loss, an improvement in the orientation of the antenna structure can be made that aims for an improvement of the signal coverage, the reduction of noise (interference), and increase of the range, capacity or data rate, etc.
The transmit power is known and relatively easy to access in the system databases. The type of antenna is typically known as all antenna manufacturers provide appropriate antenna diagrams. Similarly, the received values are known from the measurements. It is therefore of utmost importance for the optimization of antenna parameters that the original data for the position and orientation in the underlying system database correspond to the actual values.
External factors, in particular by wind and weather, improper installation, or the like, can, for example, always result in unwanted displacements of the antenna during operation.
The optimization of antenna parameters is carried out both during the construction of a mobile network, during the network expansion, i.e. during the addition of new transmission facilities both the orientation of the newly added antenna and the orientations of neighboring transmitters are to be optimized continuously, to maximize the signal coverage during operation, and to minimize interference due to the ever-increasing traffic.
To detect the position and orientation of antenna structures and for storage in databases various options are available according to the state-of-the-art.
A common method for sensing the position and orientation of antenna structures is the on-site measurement of the position using GPS system (x, y, z), the determination of azimuth alignment using compass, and the determination of antenna tilt with tilt angle encoders.
However, these methods have a number of practical disadvantages, such as:                Access restrictions on transmission facilities in operation: Without turning the active transmitter off, no measurements in the immediate vicinity of the antennas can be performed. Furthermore, access to these objects may be restricted, or very limited, e.g. power poles, homes, transmitters that are shared with other operators—which would mean a shutdown of all networks, etc. A subsequent measurement is therefore expensive and takes a long time.        High costs: Even if access is permitted, the accurate measurement requires usually expensive and thus qualified staff, eg safeguards to climb a pole, etc.        Errors due to the manual reading process: With the manual reading of measurement data errors are possible        Disturbances of the magnetic field in the immediate vicinity of the metallic masts: In the near field of an electro-magnetic transmitter a compass therefore does not always point to the north. As a result, both systematic and random measurement errors arise.        Wrong entry of data into the database: the data are almost exclusively manually entered into a database. Thus, even when the data is measured and read correctly, the manual input is another major error source.        